Lowland raised bogs

Context

Bogs are wetlands that support vegetation that is usually
peat-forming and which receive mineral nutrients principally from
precipitation rather than ground water. This is referred to
as ombrotrophic (rain-fed) mire. Two major bog types are
identified, namely raised bog and blanket bog. These two
types, are for the most part, fairly distinctive, but they are
extremes of what can be considered an ecological continuum and
intermediate (or mixed) types occur.

The vegetation of bogs which have
not been modified by surface drying and aeration or heavy grazing
is dominated by acidophilous species, such as bog-mosses
Sphagnum spp., cottongrass Eriophorum spp. and
cross-leaved heath Erica tetralix. The water-table
on these types of bogs is usually at or just below the
surface.

Raised bogs are elevated deposits of
peat in the lowlands. They are divided into active bogs, in
which the peat is still being added to, and degraded bogs in which
peat formation is at least temporarily at a standstill. The
difference is reflected in the Natura 2000 features: 'active raised
bog' and 'degraded bog still capable of natural
regeneration'. The Natura 2000 feature 'depressions in peat
substrates (Rhynchosporion)' may also be found on lowland
raised bog.

In lowland areas with predominantly
acid substrata there are examples of valley and basin mires that
receive acid surface seepage, which gives rise to vegetation
similar to that of bogs. However, these types are covered in
the Fens
and marshes reporting category.

Natura 2000 comprises Special Protection Areas (under the Birds Directive) and Special Areas for Conservation (under the Habitats and Species Directive). The list presented here includes all of the qualifying interest features under these Directives, and shows the proportion of these features for which a condition assessment has been made.

SSSI features

List of SSSI and ASSI interest features in this reporting category

Interest feature name

Formal name

Informal name

No. of assessments reported

Active raised bogs

Active raised bogs

2

Bogs

Bogs

38

Estuarine raised bog

Estuarine raised bog

2

Intermediate raised bog

Intermediate bog

3

Raised bogs

Raised bogs

75

This list has not been fully standardised at a UK level yet. It is intended to show the principal constituent "feature types" for this reporting category.

Maps - distribution

Distribution of reported interest features.

Map showing the locations of the 10km squares in which at least one condition assessment has been reported. It does not show features that have not yet been assessed.

Maps - Natura

Current condition of SAC features
Distribution of SAC features showing assessments of favourability (where unfavourable-recovering is counted as unfavourable).

Condition of SAC features, with those currently reported as unfavourable-recovering shown as favourable
The implication of the unfavourable-recovering condition assessments is that at some point in the future these features should become favourable. This map shows the effect of that recovery by counting the favourable and unfavourable-recovering assessments together.

IMPORTANT NOTE: we do not have information on the timescale of the predicted recovery, which may be influenced by many past, natural and human related factors. A sustained sympathetic management regime is more likely to result in favourable condition being attained.

Key: Proportion of assessed features on 10km squares that are favourable:

Maps - SSSI

Current condition of SSSI/ASSI features
Distribution of SSSI/ASSI features showing assessments of favourability (where unfavourable-recovering is counted as unfavourable).

Condition of SSSI/ASSI features, with those currently reported as unfavourable-recovering shown as favourable
The implication of the unfavourable-recovering condition assessments is that at some point in the future these features should become favourable. This map shows the effect of that recovery by counting the favourable and unfavourable-recovering assessments together.

IMPORTANT NOTE: we do not have information on the timescale of the predicted recovery, which may be influenced by many past, natural and human related factors. A sustained sympathetic management regime is more likely to result in favourable condition being attained.

Key: Proportion of assessed features on 10km squares that are favourable:

Condition summary

This lists the 10 different condition assessments and presents a bar chart showing the number of features within the SSSI series and the Natura 2000 series (either SPA for bird features or SAC for features other than birds). Note that for Natura 2000 we are able to estimate the number of features that have not been assessed during the 6 year reporting period - we are unable to do this for SSSI/ASSI because we do not have an overall list of notified interest features for these designations.

NB favourable unclassified and unfavourable unclassified have been used in this first six year cycle to get around difficulties in identifying trends in condition as common standards monitoring is implemented. It is expected that these categories will not be used for subsequent assessments of a feature.

Condition assessment - Natura 2000 features

The number and proportion of assessments for Natura 2000 (SAC and SPA) interest features falling into each of the condition categories. Note that the �unfavourable� category includes all reports of unfavourable condition except �unfavourable recovering� which is shown as a separate segment.

Condition assessment - SSSI features

The number and proportion of assessments for SSSI/ASSI interest features falling into each of the condition categories. Note that the �unfavourable� category includes all reports of unfavourable condition except �unfavourable recovering� which is shown as a separate segment.

Adverse activities

The number of interest features where an activity has been reported as being implicated in the "unfavourable" condition of a feature. More than one adverse activity may be reported for each feature.

Management measures

For each "measure" the chart shows the number of interest features where that measure has been taken on a site to improve or maintain the condition of an interest feature. More than one measure may be reported for each feature assessed.

Interpretation

Only a fifth (21%) of lowland raised
bogs reported are in favourable condition. This is well below
the average for terrestrial habitats, all habitats, or all features
combined. The proportion of features on A/SSSIs and SAC sites
reported in favourable condition is similar, with 22% and 19%
respectively. More of the unfavourable SAC features reported
are recovering (52%) than on A/SSSIs (35%). This no
doubtreflects the additional resources aimed at achieving
favourable condition on Natura 2000 sites. No lowland raised
bogs in England are in favourable condition, but 44% are
unfavourable-recovering.

The main causes of unfavourable
condition are water management (presumably, drainage) and lack of
remedial management (neglect). It is important to recognise
that water management (drainage) affects bog condition when carried
out within the designated site and around its borders within a
marginal area known as the hydrological protection zone.
Other important causes include invasive species (e.g. birch
Betula spp.) and under-grazing. Development carried
out under planning permission may have been under-recorded, as it
should include commercial peat extraction. It may be that the
activity is split between this category and
extraction/removal. Peat extraction is still a cause of
unfavourable condition on about 750 ha of lowland bog in England;
most of this is on two pSAC sites.

Air pollution is only cited in a few
cases. This is likely to be an under-estimate, as most
surveyors would attribute the effects of it to other causes, such
as drainage. Critical loads of sulphur are still being
exceeded for some lowland raised bogs, and are predicted to do so
at least to 2010. Dry deposition of ammonia is still very
high in most parts of England, Wales and Northern Ireland.
Bisulphite has an inhibitory effect on some Sphagnum moss
species, and deposition of nitrogen encourages rank competitors
such as the purple-moor grass Molinia caerulea.